Nearly three months ago, Khader Adnan — a Palestinian prisoner in Israel and a leader of an armed Palestinian group called Islamic Jihad — began a hunger strike to protest his detention. Adnan, who was 45, died last week.

Almost immediately, his death set off violence. That afternoon, Islamic Jihad launched more than 100 projectiles toward southern Israel. In response, Israeli officials began planning a counterassault.

A week later, Israeli missiles struck three apartments across the Gaza Strip within seconds of one another early Tuesday morning, killing three Islamic Jihad commanders as most Gazans were sleeping. The assault also killed 10 civilians, according to Palestinian officials, including some of the targets’ wives and children.

Islamic Jihad retaliated a day later, firing hundreds of rockets and shells toward Israel. Some reached the skies above the suburbs of Tel Aviv, though Israel’s air defense systems intercepted many of the rockets and prevented casualties.

Yesterday, Israeli forces killed two more of the group’s commanders and continued to bombard Islamic Jihad weapons sites. Islamic Jihad fired rockets, one of which hit an apartment building in central Israel, killing one resident — the first Israeli casualty in this round of fighting. This morning the cross-border fighting resumed, with Islamic Jihad firing rockets toward the hills around Jerusalem.

At least 31 Palestinians were killed in the hostilities, six of them children, according to Palestinian health officials. Israel said that Islamic Jihad’s own misfired rockets caused four of the deaths.

Palestinian Islamic Jihad, founded in 1981, is a hard-line organization that focuses more on armed struggle against Israel and less on engaging with the Palestinian population. It rejects Israel’s right to exist, as does its primary backer, Iran. The group’s goal is to establish an Islamic state in all the territory of historic Palestine, which includes modern Israel.

Hamas, the larger and more popular Islamic militant group that controls the Palestinian coastal enclave of Gaza, did not take part in the rocket launching, though it did voice support for Islamic Jihad.

Hamas sometimes acts in coordination with Islamic Jihad and at other times acts to restrain it. Hamas’s political wing bears responsibility for Gaza’s more than two million mostly poor residents, so it has very different interests. Operating under a blockade imposed by Israel and Egypt for security reasons, Hamas’s priorities include keeping open the border crossings between Israel and Gaza for the passage of Palestinian workers and goods.

Most likely in another shaky cease-fire, such as the one that was broken first after Adnan died and again by Israel’s deadly predawn strikes on Tuesday.

Islamic Jihad’s stated conditions for a new cease-fire included Israel’s release of Adnan’s body for burial; a halt to assassinations by the Israeli military; and the cancellation of a provocative annual parade this month marking Israel’s capture of East Jerusalem in the 1967 war.

Even once quiet has been restored, the fundamental enmity will remain. Not much will have changed on either side. The cease-fire will hold till the next round.

In November, Israelis elected the most right-wing and religiously conservative government in the country’s 75-year history. Its supporters expected it to take more aggressive action against threats from Gaza. The ultranationalist minister of national security, Itamar Ben-Gvir, even boycotted government votes in protest of what he considered to be a weak response to the heavy rocket fire last week.

It is always hard to gauge the effect of public opinion on government actions. But Prime Minister Benjamin Netanyahu, a conservative with years of experience as Israel’s longest serving premier, has long had a reputation for being risk averse and not eager for military adventures.

Israeli political and military leaders said they decided to attack Islamic Jihad’s leadership after determining that they needed to deter the group once it began firing more than 100 rockets in a day.

Such Israeli military campaigns are far from unprecedented. The previous, centrist-led government carried out missile strikes in Gaza in August that killed two senior Islamic Jihad commanders and more than 40 other Palestinians, including at least 15 children.

For Islamic Jihad, it probably makes little difference who is sitting in the Israeli government.

Lives Lived: Chris Strachwitz devoted his life to music passed down over generations — cotton-field music, orange-orchard music, mountain music, bayou music — that came from a time before there was such a thing as a music industry. He died at 91.

N.B.A. playoffs: The Nuggets eliminated the Suns last night. And the Celtics beat the Sixers, forcing Game 7 in a series that’s felt backward from the beginning.

Unheralded signing: Jourdan Heilig was working at a fast-food restaurant when the Patriots called. Now he could be a special teams ace.

It’s time for the annual Eurovision Song Contest this weekend, the international event that has helped launch acts like ABBA and Maneskin. Millions of viewers in Europe and beyond will watch the campy celebration of pop music.

Last year, the Ukrainian act Kalush Orchestra won with a track that mixed rap and folk music. The country’s act this year, the pop duo Tvorchi, will perform a song inspired by the soldiers who fought to defend the city of Mariupol. They spoke with The Times about rehearsing for the contest during air raid sirens.